Microcrystalline wax coated wrapper sheet



United States Patent M 8 Claims. (Cl. 26028.5)

The present invention relates to an improved wax composition for coating or laminating materials, for instance, paper or other fibrous or sheet materials. More particularly the present invention is intended to provide coating and laminating wax compositions of increased sealing or laminating strength at both high and low temperatures without adversely effecting other desired properties in such wax compositions.

Wax compositions have found increasingly extensive use in recent years for coating paper and paperboard materials to be used as protective and decorative wrappings for a wide variety of substances. In addition, wax compositions have been used as adhesives for laminating two or more plies of paper or other sheet material. Such coatings and laminants have found particularly extensive use in the food industry, where a wide variety of products are packaged. A few examples of such uses are bread wrappers, frozen food overwrappers, cracker and cereal box wrappers and liners, household waxed paper, drinking cups, milk cartons, laminated paper and glassine bags and pouches, and paperboard cartons laminated to liners or overwrappers.

In most of these applications it is highly desirable that the wax composition possess adhesive and cohesive strength as manifested by high heat seal strength, high laminating strength, or strong adherence to the substrate to minimize peeling, chipping and flaking. However, where wax coated paper is used as an outer wrapping, it is usually of major importance that such a coating also have high gloss, hardness, scuff resistance and blocking resistance so that the package will maintain attractiveness and sales appeal. In order to obtain these properties to the desired degree, and particularly with a wax composition having molten viscosity such that it can be coated readily with conventional waxing equipment, it is normally necessary to use a wax composition which affords less than the desired heat-scalability. Typical of wax compositions affording less than the desired heat-sealability are those into which have been incorporated small amounts of conventional polyethylene polymers of various molecular weights.

Similarly, if a wax compound having the desired sealing strength is employed, it is necessary to sacrifice gloss, hardness, blocking and scuff resistance, or resort to use of a composition containing an unduly high content of a polymer such as polyethylene, or containing a rubbery, viscous, difiicultly soluble, high molecular weight polymer such as polyisobutylene or butyl rubber. In the latter cases, cost of the coating is increased, and the high viscosity of such blends renders the composition difficult, if not impossible, to handle in coating operations employing conventional waxing equipment. Where the 3,236,795 Patented Feb. 22, 1966 package is to be stored or handled at low temperatures, as in the case of frozen foods, the problem is even more difi'icult, as most compositions affording good seal strength at low temperature are relatively soft and tacky at room temperature-a condition which creates gloss, blocking, and handling problems. The compositions of this invention alleviate these problems by (a) affording high sealing strength over an unusually wide temperature range, (b) affording excellent gloss, blocking resistance, hardness, and scuff resistance, and (c) ease of preparation and application to paper.

Wax laminants usually contain predominantly microcrystalline wax of petroleum origin, often in combination with a tacky polymeric or resinous material. Wax laminants can be softer and tackicr than coating waxes, of course, since gloss, blocking resistance, etc., are unnecessary. However, use of a relatively soft composition does not insure good laminating strength. Many commercially available microcrystalline waxes lack the inherent adhesivity required in a good laminating wax, especially if good lamination strength must be maintained at low temperatures. Incorporation of tacky, high molecular weight polymers, such as butyl rubber or polyisobutylene, may improve lamination strength, but such rubbery polymers do not blend readily with wax and must be incorporated by means of special mixers or mills. Also, when used in sufficient quantity to improve low temperature laminating strength, these rubbery additives cause a great increase in blend viscosity which renders such compositions difilcult to apply at the desired high speeds.

Ordinarily, to obtain good laminating strength at low temperature it is necessary to use a wax composition made softer by the inclusion of oil or low melting wax. However, such a composition has a greater tendency to bleed and stain the plies when exposed to normal or slightly elevated temperatures. Thus, staining is a difliculty frequently encountered as a result of soft, low melting components used to impart greater sealing or laminating strength to a wax composition. The compositions of this invention alleviate these problems by (a) aifording high laminating strength without undue softness, (b) eliminating need for rubbery, viscous, difiicultly soluble polymers, (c) permitting low viscosity and easy application, and (d) permitting utilization of waxes which normally would not be sufficiently adhesive for use as laminants.

It has been found that compositions afifording the advantages described above can be readily prepared by incorporating a minor amount of oxidized polymethylenic resin into an essentially non-aqueous petroleum wax composition consisting essentially of about 0 to by weight of a paraffin wax and about 10 to by weight of a microcrystalline wax and having about 0 to 35% by weight of a polyethylene resin. The relative amounts of each type of wax which will be used depend on the properties of the specific waxes in question, and on the intended use of the wax coating or lamination. For example, when glossy, scuff-resistant coatings are desired, paraffin waxes and relatively hard microcrystalline waxes or combinations of the two are usually used. A preferred coating wax composition will generally contain, as the petroleum wax component, about 30 to 60 weight percent of relatively hard microcrystalline wax and about 40 to 70 weight percent of paralfin wax. On the other hand, for laminations or special adhesive coatings, a relatively soft microcrystalline wax is usually, though not necessarily, the principal component. Preferred laminating wax compositions, generally, contain a wax component having about 80 to 100 weight percent of relatively soft microcrystalline wax and about to weight percent of paraffin wax. Likewise, whether or not and in what amounts, regular or unoxidized polyethlylene, as distinguished from the oxidized resin essential to my present compositions, will be used in this invention depends on the properties and proportions of the waxes employed and the intended use and desired physical properties of the wax coating or laminating composition.

The paraffin wax suitable for use in the instant invention can be a fully or semi-refined petroleum wax. In general the wax can be obtained from paratfin base crude oils such as Pennsylvania crude or mixed base crudes and will usually have a melting point of about 120 to 165 F.

The petroleum microcrystalline wax component of the present composition can be prepared, for example, by conventional solvent deoiling of petrolatum from 21 Mid- Continent crude oil or a Pennsylvania crude oil and generally has a melting point of about 100 to 180 F. As mentioned both the hard and relatively soft microcrystalline waxes find use in the present invention. The relatively soft microcrystalline waxes useful in the present invention may be identified as those microcrystalline waxes having a 100 gram needle penetration at 77 F. of about 17 to or more, and more typically of about 20 to 25. The relatively hard micnocrystalline waxes, i.e., those microcrystalline waxes usually employed in the coating compositions of the present invention are identified as having a 100 gram needle penetration at 77 F. of about 10 to 17.

The regular polyethylene resins which can be used in the present invention are any of the tough, flexible, translucent, wax-compatible, i.e., dispersible, miscible or soluble in wax, polymers of the general formula (CI-I made by polymerizing ethylene. Such polymers are common items of commerce and generally have a molecular weight of at least about 750. They differ somewhat in degree and type of branching, crystallinity, and physical specifications, and they are produced in a wide range of average molecular weights. Use of the lower molecular weight polymers (advantageously about 2,000 25,000) as wax modifiers and additives is well known to all those concerned with the art, and it is the polymers of this molecular weight group which are preferred for purposes of this invention. The type of regular polyethylene used in these compositions can be varied. Its selection, like the function it performs, will depend somewhat on the intended application. In glossy surface coatings, its function is to enhance gloss stability, hardness, toughness, cohesive strength, scuff resistance, and blocking resistance. In non-glossy coatings, which result from slow-cooling the film as, e.g., in the case of dip-coated, air-cooled cartons, polyethylene does not act as a gloss improver, but performs the other functions mentioned above, and also acts to control the degree of penetration into the substrate, and acts as a film leveling agent. When used in wax laminations, it increases cohesive strength and reduces penetration into the substrate. By varying type, amount, and molecular weight, it can also be used to regulate melt viscosity of adhesive mixtures in order to obtain optimum performance on coating or sealing equipment. If employed the proportion of polyethylene which can be used advantageously in these compositions varies from about 02-35% by weight. In most cases a concentration of from about 0.5% to about 10% will be most advantageous.

By oxidized polymethylenic resin is meant any of the hydrocarbon resins predominantly of (CH structure which have been oxidized through reaction with oxygen sufiiciently to introduce carboxylic groups. These resins have molecular weights of at least about 750, preferably at least about 2000 and are essentially of polymethylenic configuration and can be obtained from various sources, for instance by ethylene or propylene polymerization. The oxidized product is wax-compatible, i.e., dispersible, miscible or soluble in wax; however, it is preferred that the molecular weight not be greater than about 25,000. In order to realize full benefit, the degree of oxidation should be sufficient that at least one carboxylic group is introduced for each 15 average molecules, and preferably for each 1-3 average molecules. However, benefits may be obtained from lesser degrees of carboxylic content. A polyethylene resin of the above degree of oxidation substantially retains its rigidity and hardness. A preferred oxidized polyethylene resin will exhibit a needle penetration g./5 sec/77F.) of about 0.4 mm. or less. The concentration of partially oxidized polymethylenic resin which can be advantageously used in the present invention will depend on the degree of oxidation and the intended use, and generally will fall between the limits of about 0.1 to 10%, and preferably between the limits of about 0.25 to 3%. If desired, the oxidized polyethylene can be steam treated.

At least two examples of oxidized polyethylene are now commercially available. Epolene E is marketed by Eastman Chemical Products, Inc. It has an average molecular weight of about 2500, an acid number of about 8-12, and a saponification number of about 20-25. A-C Polyethylene 629, marketed by Semet-Solvay Petrochemical Division, has an average molecular weight of about 2000, an acid number of about l417, and a saponification number of about 25-30. Both Epolene E and A-C Polyethylene 629 contains about one carboxylic group for each 2 average molecules. In addition, polyethylenes of higher molecular weight can be partially oxidized to form products satisfactory for purposes of this invention. The only restriction on the molecular weight of polyethylene which can be satisfactorily utilized is that dictated by convenience of oxidation and blending. Polyethylenes having a molecular weight greater than about 25,000 have high melt viscosity and contribute to unduly high viscosity and inconvenience of blending in wax compositions.

It must be emphasized that certain low molecular weight polyethylenes which might be considered partially oxidized, since they contain oxygen as a result of the presence of hydroxyl or ester groups, are not suitable as the partially oxidized polymethylenic resin component of this invention because they do not contain carboxylic (-COOH) groups. For example, Semet Solvays G-201 Polyethylene exhibits an acid number of zero and a saponification number of about 25. Hence, Semet Solvays A-C Polyethylene 6 (originally Alcowax.

6) or Polyethylene G-201 are completely unsuited for this purpose. The hydroxyl and ester groups, respectively, claimed to be present in these molecules do not. provide the type of partial oxidation necessary to provide the strong adhesion achieved by the compositions of this invention. Manufacture and use of such hydroxyl-containing polymers is described in US. Patents 2,504,400 and 2,712,534 to M. Erchak, Jr. This is emphasized in view of US. Patent 2,698,309 to Thwaites and Hitchcox, wherein a blend of conventional high pressure polyethylene, Alcowax 6, and petroleum wax is claimed to exhibit superior blocking resistance and sealing strength. The wax coating compositions of the present invention as a result of the presence of small amounts of a carboxylic acid group containing poly- 5 methylenic resin are found to exhibit properties of sealing strength, blocking resistance, and others superior to 6 the method of Example I. Compositions and results of tests on these blends are shown in Table II.

TABLE II Composition, Wt. Percent Test Properties Sealing Blocking Gloss 75 Oxidized Strength, Temp, Glossmeter Wax Polyethylene, Polyethylene, 2 gm./3 in. (TAPPI Initial-7 Day Viscosity, Blend 1 4,000 M01. Wt. 2,000 M01. Wt. T652 SM-57) SSUI210 F.

250% Paralfin Wax B (137 F. M.P.) plus Microcrystalline Wax B (170 F. M.P., 13 needle penetration at 2 A o Polyethylene 629.

the wax composition described in the Thwaites and Hitchcox patent.

The following examples will serve to illustrate the present invention.

Example I A series of blends was prepared having the compositions shown in Table I. The blends were prepared by adding the materials to a vessel, heating to about 220 F.

Table II further illustrates the superior sealing strength of the new compositions which is obtained without sacrifice in blocking resistance, gloss, or recourse to viscous additives.

Example III Another series of blends was prepared according to the method of Example I. Compositions and results of tests on these blends are shown in Table III.

TABLE III Composition, Wt. percent Test Properties Polyethylene, Oxidized Sealing Blocking Gloss Wax Blend 1 12,000 Mol. Polyethylene, Strength, Temp, F. Glossrneter Viscosity Wt. 2,500 Mol. Wt. I in. (T652 SM57) Initial-7 Day SSU/210 F.

at 77 F.

and stirring until complete solution was obtained. About one half-hour was required for the blending operation. Results of tests on these blends are summarized in Table I.

liarafiin Wax C (152 F. MP.) plus 10% Microcrystalline Wax B (170 F. M.P., 13 Needle Penetration Table III illustrates the high sealing strength obtained in two additional compositions of this invention without sacrifice in blocking, gloss or fluidity.

TABLE I Composition, Wt. Percent Test Properties Polyethylene, Oxidized Sealing Strength, gm./3 in. Blocking Wax Blend 1 12,000 Mol. Polyethylene, 2 Temp, F. Viscosity,

Wt 2,500 Mol. Wt. (TAPPI T652 SSU/210 F.

75 F. 0 F -20 F. SM-57) i 50% Paraffin Wax A (136 F. M.P.) plus 50% Microerystalline Wax A (171 F. M.P., 13 needle penetration at 2 Epolcne E.

Table I illustrates the superior sealing strength of the oxidized polyethylene-containing wax compositions of this invention compared to a conventional product. Also 70 illustrated is the retention of blocking performance and low viscosity of the novel compositions.

Example 11 Example IV Another series of blends was prepared according to 7 and results of tests on these blends are shown in Table IV.

TABLE IV A B G D E F G H .I K

Components, Wt. percent:

Wax Component; 100 97 97 97 97 97 97 90 99. 25 89.5

Polyethylene, 4,000 Mel. Wt Polyethylene, 12,000 Mol. Wt Butyl Rubber 2 Polyisobutylene, 80,000 M01. W Oxidized Polyethylene Test Properties:

Laminating Strength, g./3 111.: At 75 F At 0 F 34 37 40 37 65 65 88 65 71 Stain Temperature, 107 125 118 115 119 127 131 130 115 137 Viscosity, SSU/210 F 77 92 148 250 879 92 125 144 81 144 1 Microcrystalline Wax C, 170 F. MB, 23 needle penetration at 77 F. 2 Copolymer of 97% isobutylene and 3% isoprene. 3 Epolene E.

The results contained in Table IV clearly illustrate that typical compositions of this invention, represented by Blends F, G, H, J and K exhibit the desired properties of high laminating strength, high stain temperature and low viscosity to a degree not at all exhibited by the wax component alone or by the Wax component to which has been added a corresponding amount of regular polyethylene. Blend J illustrates that even very minor amounts of the combination of oxidized and unoxidized polyethylene impart the desired properties to the wax to a remarkable degree. Blends D and E illustrate that use of relatively viscous, tacky polymeric materials do not insure the desired laminating strength, even when used at a concentration high enough to cause considerable viscosity increase in the blend.

Example V Another series of blends was prepared according to the method of Example I to show the eifects of adding oxidized polyethylene alone to microcrystalline wax. The

1 Microcrystalline Wax 0, 170 F., M.P., 23 needle penetration at 77 F. 7 "Epolene E.

The data demonstrate that the addition of conventional polyethylene although beneficial in certain respects, is not necessary to obtain the principal benefit of the above laminating compositions, i.e., high laminating strength over a wide temperature range, ease of preparation, economy, and utilization of microcrystalline wax having limited laminating strength. Furthermore, the data show that staining tendency is decreased.

Example VI Another series of blends was prepared according to the method of Example IV. A relatively soft microlcrystalline wax component was used in these blends in order to demonstrate the very high low-temperature laminating strength afforded by the compositions of this Polyethylene, 4,000 Mol. Wt.

Oxidized Polyethylene A Butyl Rubber 1 Test Properties: Laminating Strength, g./3 in.

4 168 F. M.P., 29 needle penetration at 77 F., derived from Mid- Continent Crude.

2 Epolene E.

Blend M illustrates that very strong seal strength can be readily achieved with a typical composition of this invention, even at very low temperature, and in spite of the weak sealing characteristics of Microcrystalline Wax D, the principal component.

Example VII A series of blends was prepared according to the method of Example IV above. Compositions and results of tests on these blends are shown in Table VII.

TABLE VII Components, Wt. percent:

Parafiin Wax A 1 99 97 97 97 89 87 89 87 87 88 Microcrystalline Wax A 10 10 10 10 10 10 Polyethylene, 12,000 Mol. Wt 3 1 3 Polyethylene, 2,500 Mol. Wt 3 3 Polyisobutylene, 80,000 Mol. Wt 2 Oxidized Polyethylene, 2,500 Mol. Wt. 1 Test Properties:

Sealing Strength, g./3 in.:

At F 32 33 30 33 44 44 32 33 26 21 At 0 F 43 36 33 30 57 57 41 30 30 25 Blocking Point, F. 102 101 101 117 102 101 114 111 Viscosity, SSU/210 F- 43 59 47 59 350 1 137 F. M.P., fully-refined crystalline wax irom Mid-Continent petroleum. 2 171 F. MB, 13 needle penetration at 77 F., refined mieroerystalline wax from Mid-Continent petroleum.

3 Epolene E.

Results of tests on Blends 1-4 illustrate that oxidized polyethylene is no :more effective than unoxidized polyethylene for improving sealing strength of a conventional, refined paraflin wax. However, when oxidized polyethylene is added to a wax blend containing about 5 microcrystalline wax as in Blends 5 and 6, sealing strength is significantly improved. Contrarily addition of unoxidized polyethylene to such a wax blend as illustrated by Blends 7-9, does not result in significantly increased sealing strength. Table VII also illustrates that oxidized polyethylene is at least equal and in some cases superior to unoxidized polyethylene in imparting blocking resistance to wax. Furthermore, it does not cause unduly high blend viscosity as does polyisobutylene in Blend 10. If a high degree of gloss retention is desired, this can easily be obtained by using both oxidized and unoxidized polyethylene, as illustrated in the examples above.

Example VII, of course, cites results for a borderline case. Coating waxes of much higher sealing strength can be prepared by increasing the ratio of microcrystalline wax to parafiin wax, and I prefer at least about 25% of the microcrystalline wax. This is illustrated by Example VIII.

Example VIII A series of blends was prepared according to the method of Example VI. Compositions and results of tests on these blends are shown in Table VIII.

TABLE VIII 158 60 At 0 F 98 38 32 Blocking Point, F. (T652 SM-57) 115 115 115 40 1 "Epolene E."

The results clearly illustrate the superior sealing strength exhibited by a blend of paraflin and microcrystalline waxes containing a small amount of partially oxidized polyethylene over a similar wax blend containing regular or unoxidized polyethylene.

Values for sealing strength and laminating strength reported in the above tables were determined by coating a bleached sulfite paper of 25 lbs/ream (3000 ft?) basis weight with a surface coat of 5 lb./rm. of the composition to be tested. The reverse side of the paper was coated with 2-3 lbs./rm. A test specimen was then prepared by sealing together two sheets, face to face by drawing the sheets over a sealing roll, 2.5 inches in diameter, and maintained at 210 F. by internal circulation of steam -the resulting seals being allowed to cool in air. The plies were drawn across the sealing roll at 25 inches per minute, traveling vertically upward against the side of the roll and passing over a sufficient sector that the angle of departure from the roll was 60 with the horizontal. The outermost ply was loaded at the trailing end with a 200 gram weight to supply a controlled sealing pressure. The plies thus sealed were trimmed to 10" x 3", aged for 24 hours at 73 F. and 50% RH, and desealed using an Instron Tensil Tester. Seals tested at low temperatures were conditioned for at least 2 hours at test temperature prior to testing. All tests were run in triplicate. It should be noted that the test for laminating strength and sealing strength is one and the same and whether one calls it a laminating strength test or sealing strength test is a matter of terminology. Generally, however, seal strength is used in reference to wax compositions characterized by being hard, scuff resistant, probably glossy, etc., while laminating strength is used with reference to wax com- 10 positions being somewhat softer and having no requirements as to scuff, gloss and blocking point.

Values for stain temperatures were determined by coating cellophane with 6080 lbs/ream on one side only, placing a one-inch wide strip between two strips of 60 lbs./ rm. unbleached kraft and testing the resulting sandwich on a temperature gradient blocking plate under the conditions described in the TAPPI T652 SM-57 gradient blocking test. The staining temperature was taken as the lowest temperature at which the kraft strip in contact with the wax coating showed definite staining across the entire width of the interior side.

In summary, it has been found that inclusion of minor amounts of oxidized polymethylenic resin markedly increases the adhesive strength of a wide variety of petroleum wax compounds, both at ordinary and low temperatures, and without adversely affecting hardness, blocking and scuff resistance, and other desirable properties, and without creating undue viscosity increase. In addition, if a minor amount of conventional polyethylene additive is incorporated in the composition to provide gloss stability blocking resistance, cohesive strength, toughness, scuff resistance, leveling action, decreased staining tendencies, control of penetration into the substrate, or such of these properties as may be desired, the resulting compositions exhibit markedly superior performance compared to previous compositions. By varying the characteristics of the base petroleum wax or waxes, and by using appropriate amounts of oxidized polyethylene or oxidized polyethylene and regular polyethylene, it is possible to produce superior waxes which can be used to coat cellulosic materials such as wood, paper, paperboard, fibrous or non-fibrous films.

Similarly, superior waxes can be produced for laminating two or more plies of fibrous or non-fibrous cellulosic materials such as wood, paper, cellophane and other sheet materials like metal foil.

This application is a division of application Serial No. 751,178, filed July 28, 1958, now US. Patent No. 3,117,101.

I claim:

1. A wrapping sheet material coated with a wax composition having a Wax component consisting essentially of about 0 to by weight of petroleum paraffin wax, about 10 to of a petroleum rnicrocrystalline wax having a 100 gram needle penetration at 77 F. of at least about 10, and having about 0 to 35% by weight of a Waxcompatible polyethylene resin and about 0.1 to 10% of wax-compatible carboxyl group-substituted oxidized polyethylene having at least one carboxylic group for each 15 average molecules, a saponification number of about 20 to 30 and an acid number of about 8 to 17 and having a molecular weight of at least about 750, said wax composition excluding stearates and soaps.

2. An article of manufacture consisting essentially of sheet materials laminated with a wax composition having a wax component consisting essentially of about 0 to 90% by weight of petroleum paraffin wax, about 10 to 100% of a petroleum microcrystalline wax having a 100 gram needle penetration at 77 F. of at least about 10, and having about 0 to 35 by weight of a wax-compatible polyethylene resin and about 0.1 to 10% of wax-compatible carboxyl group-substituted oxidized polyethylene resin having at least one carboxylic group for each 15 average molecules, a saponification number of about 20 and 30 and an acid number of about 8 to 17 and having a molecular weight of at least 750, said wax composition excluding stearates and soaps.

3. A wrapping sheet material coated with the composition of claim 2 wherein the amount of polyethylene resin present is about .5 to 10% by weight and the amount of oxidized polyethylene resin incorporated is about .25 to 3% by weight.

4. An article of manufacture consisting essentially of sheet materials laminated with the composition of claim 2 wherein the amount of polyethylene resin present is about .5 to 10% by weight and the amount of oxidized polyethylene resin incorporated is about .25 to 3% by weight.

5. A wrapping sheet material coated with a wax composition having a wax component consisting essentially of about 40 to 70% by weight of petroleum paraffin wax and about 30 to 60% by weight of petroleum microcrystalline wax having a 100 gram needle penetration at 77 F. of about 10 to 17 and having about to 35% by weight of a wax-compatible polyethylene resin and about 0.1 to by weight of a wax-compatible carboxyl groupsubstituted oxidized polyethylene resin containing at least one carboxylic group for each average molecules, a saponification number of about 20 to and an acid number of about 8 to 17 and having a molecular weight of at least about 750, said wax composition excluding stearates and soaps.

6. An article of manufacture consisting essentially of sheet materials laminated with a wax composition having a wax component consisting essentially of about 80 to 100% by weight of petroleum microcrystalline wax having a 100 gram needle penetration at 77 F. of about 17 to 30 and about 0 to 20% by weight of petroleum parafiin wax and having about 0 to by weight of a wax-compatible polyethylene resin and about .1 to 10% by Weight of a wax-compatible carboxyl group substituted oxidized polyethylene resin containing at least one earboxylic group for each 15 average molecules, a saponification number of about 20 to 30 and an acid number of about 8 to 17 and having a molecular weight of at least about 750, said wax composition excluding stearates and soaps.

7. A wrapping sheet material coated with a wax composition having a wax component consisting essentially of about to by weight of petroleum paraffin wax and about 30 to 60% by weight of petroleum microcrystalline wax having a 100 gram needle penetration at 77 F. of about 10 to 17 and having about 0.5 to 10% by weight of a wax-compatible polyethylene resin and about .25 to 3% by weight of a wax-compatible carboxyl groupsubstituted oxidized polyethylene resin containing at least one carboxylic group for each 1 to 3 average molecules, a saponification number of about 20 to 30 and an acid number of about 8 to 17, the polyethylene resin and oxidized polyethylene resin each having a molecular weight of about 2000 to 25,000, said wax composition excluding stearates and soaps.

8. An article of manufacture consisting essentially of sheet materials laminated with a Wax composition consisting essentially of about 80 to by weight of petroleum microcrystalline wax having a 100 gram needle penetration at 77 F. of about 17 to 30 and about 0 to 20% by weight of petroleum paraffin wax and having about .5 to 10% by weight of a wax-compatible polyethylene resin and about .25 to 3% by weight of a waxcompatible carboxyl group-substituted oxidized polyethylene resin containing at least one carboxylic group for each 1 to 3 average molecules, at saponification number of about 20 to 30 and an acid number of about 8 to 17, the polyethylene resin and oxidized polyethylene resin each having a molecular weight of 2000 to 25,000, said wax composition excluding stearates and soaps.

References Cited by the Examiner UNITED STATES PATENTS 12/1954 Thwaites et al 260-285 6/1960 Rosenbaum 260-285 

1. A WRAPPING SHEET MATERIAL COATED WITH A WAX COMPOSITION HAVING A WAX COMPONENT CONSISTING ESSENTIALLY OF ABOUT 0 TO 90% BY WEIGHT OF PETROLEUM PARAFFIN WAX, ABOUT 10 TO 100% OF A PETROLEUM MICROCRYSTALLINE WAX HAVING A 100 GRAM NEEDLE PENETRATION AT 77*F. OF AT LEAST ABOUT 10, AND HAVING ABOUT 0 TO 35% BY WEIGHT OF A WAXCOMPATIBLE POLYETHYLENE RESIN AND ABOUT 0.1 TO 10% OF WAX-COMPATIBLE CARBOXYL GROUP-SUBSTITUTED OXIDIZED POLYETHYLENE HAVING AT LEAST ONE CARBOXYLIC GROUP FOR EACH 15 AVERAGE MOLECULES, A SAPONIFICATION NUMBER OF ABOUT 20 TO 30 AND AN ACID NUMBER OF ABOUT 8 TO 17 AND HAVING A MOLECULAR WEIGHT OF AT LEAST ABOUT 750, SAID WAX COMPOSITION EXCLUDING STEARATES AND SOAPS. 